Log in and click on 'My Account' at the very top. Then select 'Interactive (Devices & Tokens)' on the left. Then beside your device, there is a link to 'resend all recordings'. If this works correctly, I assume it should send all the timers to the BW again, including those it has already sent.
As for the actual error message, I guess IceTV will have to find this error and display a nice message saying that 'you already have this show set to record' instead.